The invention relates to a gas turbine engine having a mixed-flow compressor and a connecting mixed-flow diffuser.
Gas turbine engines with a known arrangement of the mixed-flow compressor and the mixed-flow diffuser arranged behind it have the disadvantage of a larger overall length in comparison to gas turbine engines with a radial-flow compressor and a radial-flow diffuser arranged behind it.
It is another disadvantage of the known arrangement of mixed-flow compressors in gas turbine engines that the combustion chambers are acted upon by compressor air according to the uniflow method so that compressor air which is disadvantageously heated by the outer wall of the flame tube is admixed to the hot gas flow as temperature-reducing tertiary air in the outlet area of the flame tubes.
It is an object of the invention to provide a gas turbine engine of the above-mentioned type which, while the compressor output which can be reached by means of a radial-flow compressor is unchanged, has a smaller outside radius while the overall length is reduced or is at least equal.
This object is achieved in that the mixed-flow diffuser is arranged inside an annular combustion chamber or an annulus formed of several annularly arranged individual combustion chambers.
It is an advantage of the solution according to the invention that the overall length of the mixed-flow diffuser does not extend the total length of the gas turbine engine because it is arranged radially inside the combustion chamber. As a result, the gas turbine engine becomes more compact and smaller in its radius than a gas turbine engine with the same compressor output having a radial-flow compressor, a radial-flow diffuser connected behind it and an elbow for deflecting the flow into the horizontal level. Furthermore, the rotor of the mixed-flow compressor was optimized with respect to the rotor rings, the rotor diameter and the deceleration conditions. Rotor blades which were considerably bent in front were found to be particularly advantageous for having a strong deceleration effect in this area.
A preferred development of the invention is achieved in that the mixed-flow diffuser is arranged in a common annular housing with an annular combustion chamber or with annularly arranged individual combustion chambers. This advantageously improves the compactness of the gas turbine engine. At the same time, the inside and outside radius of the mixed-flow diffuser can be reduced from the annular inlet opening to the annular outlet opening without impairing the operation of the diffuser. This advantage cannot be achieved by means of a radial-flow compressor with a radial-flow diffuser connected behind it.
A deflecting chamber and a deflecting wall are preferably provided for deflecting the compressor air from the outlet of the mixed-flow diffuser to the combustion chambers arranged radially on the outside. In the deflecting chamber, the compressed air is advantageously swirled and is supplied to the combustion chamber along the shortest path on the deflecting wall.
By means of the preferred arrangement of the deflecting wall in the outlet area of the combustion chambers, the combustion chambers or the annular combustion chambers are acted upon by compressor air in the reverse flow. As a result, unheated compressor air, as temperature-lowering tertiary air, is advantageously admixed to the hot gas flow in the outlet area of the flame tubes.
The compressor output can preferably be increased in that a multi-stage axial-flow compressor is connected in front of the mixed-flow compressor. This arrangement has the advantage that the deflecting chamber and the deflecting wall are supplied with an increased compressor air pressure.
A part of the deflecting wall may be formed by a part of a turbine disk, preferably by the radially outside area of the turbine disk of the first turbine stage. As a result, material and weight may advantageously be saved, and the turbine disk is cooled at the same time.
A preferred construction of the deflecting wall provides a circumferential seal between the interior wall of the deflecting chamber and the turbine disk of the first turbine stage, the circumferential seal being arranged at the interior edge of the deflecting wall formed by the turbine disk. As a result of this construction of the interior wall of the deflecting chamber and of the circumferential seal at the interior edge of the turbine disk, the whole deflecting wall is advantageously formed by one part of the turbine disk. It is another advantage of this arrangement that a portion of the compressor air can be supplied to additional consuming devices without additional connecting elements, such as co-rotating cover disks on the turbine disk. In a preferred development of the invention, openings are therefore provided in the edge area of the turbine disk which supply cooling ducts of turbine blades located in the edge area of the turbine disk with a portion of the compressor air which is available at the outlet of the mixed-flow diffuser.
Additional advantages can be achieved by means of the invention in that a bearing chamber of a turbine shaft is preferably arranged radially inside the mixed-flow diffuser. By means of this arrangement, the bearing chamber is protected from the heat of the combustion chambers which are arranged radially on the outside.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.